1. Field of the Invention
The present invention relates to a defect inspection device and an inspecting method thereof. More particularly, the present invention relates to a defect inspection device and an inspecting method thereof with using an electron beam.
2. Description of the Related Art
With the continuous research in the technique of fabricating ultra large scale integrated circuits, the level of integration of integrated circuits on a wafer increases many folds. As circuits and devices are miniaturized, very small manufacturing defects have become a significant factor affecting overall quality of the product. In the past decade, defect inspection for detecting manufacturing defects has become a part of the standard manufacturing procedure. Typically, defect inspection is a statistical sampling procedure that applies to defect prone or defect sensitive manufacturing steps.
The conventional method of detecting defects on a wafer is basically a trial and error method. First, a defect inspection parameter is set and a wafer scanning is carried out. According to the defect signal, the operator singles out and opens up the defective device to perform an inspection to confirm if the device is really a defective device. If the device is really defective, the defect inspection parameter can be used to inspect the same batch of wafers. If the device is found not to be defective, the defect inspection parameter is reset and another inspection is performed until a device returning a defect signal is actually defective. Although the aforementioned trial and error method of finding the inspection parameter is effective, the procedure is long and tedious.
In another inspection method disclosed in U.S. Pat. No. 6,451,185 B1, an optical inspection device is used to detect purposely laid defective elements on a wafer so that a suitable defect inspection parameter is obtained. The parameter is then applied to perform a subsequent inspection. However, the defective elements purposely laid on the wafer are subjected to certain character restrictions imposed by defect detection with an optical inspection device. For example, the defective element must have a reflective upper surface so that the type of material that can be used for forming the defective element is limited. Furthermore, the need to fabricate these defective elements increases the complexity of fabricating the original wafer.